FIG. 57 is a schematic front cross-sectional view showing a plating process apparatus as illustrated in Patent Document 1, serving as a type of conventional surface treatment apparatuses for small objects. This plating process apparatus 1 is formed so as to energize (turn on electricity) a plating solution 4 within a treatment cell 2 from an electrode 45 while bringing small objects 100 into contact with an electrode ring 21 and circulating the plating solution 4 from the inside of the treatment cell 2 to the outside thereof by rotating the treatment cell 2 containing the small objects 100 with a vertical rotation shaft 3, thereby plating the small objects 100. The treatment cell 2 has a flow-out means for circulating the plating solution 4 from the inside of the treatment cell 2 to the outside thereof. In the plating process apparatus 1, the plating solution 4 is discharged from a nozzle 41 to the inside of the treatment cell 2, flowed out and scattered from the treatment cell 2 through the flow-out means, received and collected by a case 42, and discharged from the nozzle 41 by a pump 43. In other words, the plating solution 4 is repeatedly used while being cycled. Furthermore, in the plating process apparatus 1, a porous ring 22 is used as the flow-out means. The porous ring 22 is formed by sintering granular resin, internally has openings, and functions as a filter that prevents small objects from passing therethrough but allows only the plating solution 4 to pass therethrough. The plating solution 4 passes through the openings of the porous ring 22.
On the other hand, a flow-out means serving as an alternative to the porous ring 22 seems to be illustrated in Patent Document 2, whereas its details are uncertain.
[Patent Document 1] Japanese Patent No. 3126867.
[Patent Document 2] U.S. Pat. No. 5,879,520.